The Mas 54 was a replacement for the Mas 49/56 semi auto rifle. One thing on it was unusual: the carbine version was in bullpup design and the rifle and standard variants were in the standard configuration. It is loaded with 20 round magazines with 7.62x51mm NATO cartridges. The Mas 54 was made entirely out of metal so it was too heavy to operate functionally. It was replaced by the more effective FAMAS assault rifle.